Method for roughening copper surfaces for bonding to substrates

ABSTRACT

The invention is directed to a method and composition for providing roughened copper surfaces suitable for subsequent multilayer lamination. A smooth copper surface is contacted with an adhesion promoting composition under conditions effective to provide a roughened copper surface, the adhesion promoting composition consisting essentially of an oxidizer, a pH adjuster, a topography modifier, and a uniformity enhancer. A coating promoter may be used in place of the uniformity enhancer or in addition to the uniformity enhancer. The adhesion promoting composition does not require a surfactant. The process may further comprise the step of contacting the uniform roughened copper surface with a post-dip, wherein the post-dip comprises an azole or silane compound or a combination of said azole and said silane. The post-dip may further comprise, alone or in combination, a titanate, zirconate, and an aluminate. The pH adjuster is preferably sulfuric acid and the oxidizer is preferably hydrogen peroxide. A hydrogen peroxide stabilizer may be used in the adhesion promoting composition.

RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.10/660,826 filed Sept. 12, 2003, which is a continuation of U.S. patentapplication Ser. No. 10/028,955 filed Dec. 18, 2001, which is adivisional of U.S. patent application Ser. No. 09/479,089 filed Jan. 7,2000. The '826, '955 and '089 applications are incorporated herein byreference in their entirety.

BACKGROUND OF THE INVENTION

This invention relates to preparing copper surfaces for bonding tosubstrates used in the manufacture of printed circuit boards (PCB's).More particularly, the invention relates to the manufacture ofmultilayer PCB's.

Multilayer PCB's are constructed by interleafing imaged conductivelayers of copper with dielectric layers to make a multilayer sandwich.The dielectric layers are organic resin layers that bond the copperlayers together. The layers of copper and dielectric are bonded togetherby the application of heat and pressure. The surface of the copper issmooth and does not bond easily to the dielectric layer.

Improved bonding can be achieved by etching or otherwise roughening thesurface of the copper to provide microscopic crevices and ridges in thesurface of the copper. The copper surface may be roughened mechanically.However, delicate circuit patterns are susceptible to damage ifmechanically roughened. Thus, there is a need for a copper surfaceroughening process that does not require mechanical roughening of thecopper surface.

Oxide processes are also known in which an oxide having a rough surfaceis formed on the copper surface. The oxide may be formed by chemicaltreatment of the copper. Oxide processes have many shortcomings. Atypical oxide process is run at such high temperatures that thesubstrate is often distorted, leading to quality control problems andadditional production costs. The oxidation process is also associatedwith uniformity problems in which portions of the copper surface are notoxidized or coated by the oxidizing solution. Uniformity problems leadto partial delamination in the multilayer PCB's. To avoid this problemthe PCB is run through multiple passes to obtain a more uniform oxidecoating. Performing multiple passes adds considerably to productioncost. Thus, there is a need for a copper roughening process that doesnot require multiple passes or high temperature.

Multilayer PCBs tend to have a sharp transition between each layer ofetched copper surface and each layer of organic resin. Thus, there is aneed for a coating promoter to facilitate the adhesion of the organicresin to the roughened copper surface.

U.S. Pat. No. 4,512,818 describes a treatment solution for the formationof a black oxide on copper surfaces of multi-layered printed circuits.The treatment solution comprises an oxidant and a hydroxide and ischaracterized by the addition of a water soluble or dispersible polymerto regulate the properties of the black oxide solution.

It is reported that major drawbacks of the black oxide procedure includemarginal bond strengths and high temperature processing. Resultingsurface coatings are prone to mechanical damage and partial delaminationaround through-holes; this problem is called “pink ring.” Pink ring iscaused by the removal of the bonding oxide layer by through-holecleaning and electroplating chemicals. Thus, there is a need for aformulation that is less prone to cause pink ring problems.

U.S. Pat. No. 5,861,076 describes a bond enhancement process forpromoting strong, stable adhesive bonds between surfaces of copper foiland adjacent resin impregnated substrates or superimposed metallicsublayers. According to the process of the invention, a blackoxide-coated copper surface is treated with an aqueous reducing solutioncontaining sodium metabisulfite and sodium sulfide to convert the blackoxide coating to a roughened metallic copper coating. The roughenedmetallic copper-coated surface is then passivated and laminated to aresin impregnated substrate.

In the chemical oxide modification process a strong reducing agent,typically dimethylamine borane, is applied to the oxide coating toobtain an even oxide coating. This type of adhesion promotion processproduces an oxide coating that is fragile and prone to scratching duringhandling. Inspection of the circuitry prior to lamination is difficultbecause of the fragility of the oxide coating. Therefore, there is aneed for an adhesion promotion process that permits a less problematicinspection after the adhesion promotion process and prior to thelamination step.

A method for roughening copper or copper alloy surfaces is described inU.S. Pat. No. 5,532,094. The copper surface is treated with an aqueoussolution comprising an azole compound, a soluble copper compound, anorganic or inorganic acid and a halogen ion.

U.S. Pat. No. 5,073,456 is directed to the manufacture of multilayerprinted circuit boards having a number of through-holes that are formedby employing intermediate layers when bonding copper circuitry to aninsulating layer.

U.S. Pat. Nos. 3,756,957, and 5,800,859 describe a range of hydrogenperoxide stabilizers; U.S. Pat. Nos. 3,756,957 and 5,800,859 are herebyincorporated by reference in their entirety. Alpha Metals sells anadhesion promoting solution under the registered trademark “Alpha Prep.”

U.S. Pat. No. 5,800,859 describes a process for providing copper coatingprinted circuit boards. The process includes a treating step in which ametal surface is contacted with an adhesion promotion material. Theadhesion promotion material includes 0.1 to 20% by weight hydrogenperoxide, an inorganic acid, an organic corrosion inhibitor and asurfactant. The surfactant is preferably a cationic surfactant, usuallyan amine surfactant and most preferably a quaternary ammoniumsurfactant.

BRIEF SUMMARY OF THE INVENTION

Accordingly, an object of this invention is to provide a copper surfaceroughening process that does not require mechanical roughening of thecopper surface.

Another object is to provide a copper roughening process that does notrequire multiple passes or high temperature.

Another object is to provide a copper roughening process that does notrequire a highly alkaline solution.

A further object is to provide a composition that optionally comprises acoating promoter.

Another object is to provide a simpler process to produce a roughenedcopper surface that is not reliant on a cationic surfactant to achieveexcellent copper surface area.

At least one of these objects is addressed, in whole or in part, by thepresent invention. The invention is a composition and method forroughening a copper surface in order to provide higher bond strengthsbetween the copper and dielectric resin layers in a multilayer PCB. Thecomposition consists essentially of an oxidizer, a pH adjuster, atopography modifier, and at least one of a uniformity enhancer and acoating promoter.

BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a schematic figure of a five membered aromatic fusedN-heterocyclic ring compound with one to three nitrogen atoms in theN-heterocyclic ring. The nitrogen atom at the #1 position in the fusedring is bonded to a hydrogen atom.

FIG. 2 is the molecular structure of 1H-tetrazole (CAS 288-94-8).

FIG. 3 is the molecular structure of derivatives of 1H-tetrazole (CAS288-94-8).

FIG. 4 is the molecular structure of a five membered aromatic fusedN-heterocyclic ring compound with 1 to 3 nitrogen atoms in the fusedring, wherein none of the 1 to 3 nitrogen atoms in the fused ring isbonded to a hydrogen atom.

FIG. 5 is an scanning electron microscopic (“SEM”) photograph of acopper surface that has been roughened according to the presentinvention, using as a treatment formulation: 3% H202, 5% H2S04, 1.0 g/lBTA, 0.5 g/l 1-hydroxybenzotriazole (coating promoter), balance DI. Thecopper surface has been uniformly etched and covered in anorganometallic coating.

DETAILED DESCRIPTION OF THE INVENTION

While the invention will be described in connection with one or moreembodiments, it will be understood that the invention is not limited tothose embodiments. On the contrary, the invention includes allalternatives, modifications, and equivalents as may be included withinthe spirit and scope of the appended claims.

As noted above, one aspect of the present invention is a composition forroughening a copper surface, consisting essentially of an oxidizer, a pHadjuster, a topography modifier, and at least one of a uniformityenhancer and a coating promoter.

The oxidizer is preferably hydrogen peroxide and is preferably presentin the range between about 0.1% and 5% (proportions of hydrogen peroxidein this specification are based on the use of 50 wt. % hydrogen peroxidein aqueous solution unless otherwise indicated) and more preferably inthe range between about 0.1% and about 2%. Alternatively, the hydrogenperoxide is preferably present in the range between about 1% and 3.5%(based on 50 wt. % hydrogen peroxide) and more preferably in the rangebetween about 1% and 2% (based on 50 wt. % hydrogen peroxide).

A hydrogen peroxide stabilizer is not required to practice thisinvention. However, a hydrogen peroxide stabilizer may be used.Non-limiting examples of optional hydrogen peroxide stabilizers include:alkyl monoamines having 2 to 10 carbon atoms, and their salts;polymethylenediamines having 4 to 12 carbon atoms and their salts;alkoxyamines formed by substituting at least one hydrogen atom ofammonia by an alkoxy radical having 2 to 6 carbon atoms and alkoxyaminesformed by substituting at least one hydrogen atom connected with thenitrogen atom of an alkyl monoamine having 2 to 10 carbon atoms by analkoxy radical having 2 to 6 carbon atoms; alkyl acyl radical formed bysubstituting at least one hydrogen atom of ammonia by an alkyl acylradical having 3 to 6 carbon atoms, and at least one alkyl acid amideformed by substituting at least one alkyl monoamine having 2 to 10carbon atoms by an alkyl acyl radical having 3 to 6 carbon atoms;alicyclic imines having a 5 to 8 membered ring; mono-n-propylamine,di-n-propylamine, tri-n-propylamine and hexamethylenediamine;octylamine; and propionylamide.

The choice of pH adjuster is not critical. Any suitable organic orinorganic acid may be used, although nitric acid is not preferred.Non-limiting examples of suitable acids include sulfuric, phosphoric,acetic, formic, sulfamic, and hydroxy-acetic acid. Sulfuric acid is thepreferred pH adjuster. Sulfuric acid is present in the range betweenabout 0.01% and 20% by weight and alternatively in the range betweenabout 0.5% and 10% by weight.

Suitable topography modifiers are five membered aromatic fusedN-heterocyclic ring compounds (hereinafter “N-heterocyclic compounds”)with at least one nitrogen atom in the N-heterocyclic ring. At least oneof the nitrogen atoms in the heterocyclic ring is bonded directly to ahydrogen atom. The nitrogen atom at the #1 position in the heterocyclicring is preferably bonded to a hydrogen atom (see FIG. 1). Non-limitingexamples of suitable topography modifiers include 1H-benzotriazole (CASregistration number, “CAS”: 95-14-7), 1H-indole (CAS 120-72-9),1H-indazole (CAS 271-44-3), and 1H-benzimidazole (CAS 51-17-2).Derivatives of N-heterocyclic compounds suitable as topography modifiersinclude N-heterocyclic compounds with a hydrogen atom bonded to thenitrogen atom at the #1 position in the heterocyclic ring. The Rsubstituents on the aromatic ring (see FIG. 1) may be alkyl,hydroxyalkyl, aminoalkyl, nitroalkyl, mercaptoalkyl, or alkoxy groupscontaining from 1 to about 10 or more carbon atoms. Specific examples ofalkyl groups include methyl, ethyl, propyl, isopropyl, n-butyl,sec-butyl, tert-butyl, amyl, etc.

Non-limiting examples of suitable derivatives of 1H-benzotriazole (CAS95-14-7) suitable for use as topography modifiers include:5-methyl-1H-benzotriazole (CAS 136-85-6), 6-Nitro-1H-benzotriazole (CAS2338-12-7), 1H-naphtho(1,2-d)triazole (CAS 233-59-0), and1H-Naphtho[2,3-d]triazole (CAS 269-12-5).

Non-limiting examples of suitable derivatives of indole (1H-Indole; CAS120-72-9) suitable for use as topography modifiers include:5-Aminoindole (1H-Indol-5-amine; CAS 5192-03-0), 6-methylindole(1H-Indole, 6-methyl-; CAS 3420-02-8), 1H-indole-5-methyl (CAS614-96-0), 7-methylindol (1H-Indole, 7-methyl-; CAS 933-67-5),3-methylindole (1H-Indole, 3-methyl-; CAS 83-34-1), 2-Methylindole(2-Methyl-1H-indole; CAS 95-20-5), 1H-Indole, 3,5-dimethyl- (CAS3189-12-6), 2,3-Dimethylindole (1H-Indole, 2,3-dimethyl-; CAS 91-55-4),and 2,6-dimethylindole (1H-Indole, 2,6-dimethyl-; CAS 5649-36-5).

Non-limiting examples of suitable derivatives of 1H-indazole (CAS271-44-3) suitable for use as topography modifiers include:1H-Indazol-5-amine (CAS 19335-11-6) and 3-Chloro-1H-indazole (CAS29110-74-5).

Non-limiting examples of suitable derivatives of 1H-benzimidazole (CAS51-17-2) suitable for use as topography modifiers include:2-Hydroxy-1H-benzimidazole (CAS 615-16-7), 2-Methyl-1H-benzimidazole(CAS 615-15-6), and 2-(methylthio)-1H-Benzimidazole (CAS 7152-24-1).

The topography modifier is preferably present in the range between about0.1 g/l (grams per liter) and 20 g/l and more preferably in the rangebetween about 0.5 g/l and 7 g/l. For example, 1H-benzotriazole can bepresent in the range between about 0.1 g/l (grams per liter) and 20 g/land more preferably in the range between about 0.5 g/l and 7 g/l.

The inventors present the following theory of operation of thisinvention. The present invention is not limited to processes or productsthat operate as specified by this theory. Any inaccuracy in this theorydoes not limit the scope of the present invention. The topographymodifier is thought to vary the surface characteristics of the copperduring treatment of the copper surface with the adhesion promotingsolution of the invention. During treatment with the adhesion promotingsolution of the invention, the copper surface is believed to comprise acomplex of copper together with the topography modifier to produce agreater surface area than would be possible without the topographymodifier. The topography modifier is essential to the invention becauseit has a beneficial effect on peel strength. Peel strength isdramatically reduced if the topography modifier is not used in theadhesion promoting solution.

The uniformity enhancer is a tetrazole such as 1H-tetrazole (CAS288-94-8, FIG. 2) and its derivatives (FIG. 3). Non-limiting examples ofsuitable tetrazole derivatives that can be used in the present inventionas a uniformity enhancer include: 5-aminotetrazole (CAS 5378-49-4),5-methyltetrazole (CAS 4076-36-2), 5-methylaminotetrazole (CAS53010-03-0), 1H-tetrazol-5-amine (CAS 4418-61-5), 1H-tetrazol-5-amine,N,N-dimethyl- (CAS 5422-45-7), 1-methyltetrazole (CAS 16681-77-9),1-methyl-5-mercaptotetrazole, 1,5-dimethyltetrazole (CAS 5144-11-6),1-methyl-5-aminotetrazole (CAS 5422-44-6), and1-methyl-5-methylamino-tetrazole (CAS 17267-51-5).

Referring to FIG. 3, the R1 and R2 substituents on the tetrazole ringmay be hydroxyl, amino, alkyl, hydroxyalkyl, aminoalkyl, nitroalkyl,mercaptoalkyl, or alkoxy groups containing from 1 to about 10 or morecarbon atoms. Specific examples of alkyl groups include methyl, ethyl,propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, amyl, etc.

The optional coating promoter is a five membered aromatic fusedN-heterocyclic ring compound with 1 to 3 nitrogen atoms in the fusedring, wherein none of the 1 to 3 nitrogen atoms in the fused ring arebonded to a hydrogen atom (see FIG. 4). Non-limiting examples ofoptional coating promoters suitable for use in the present inventioninclude: 1-hydroxybenzotriazole (CAS 2592-95-2), 1-methylindole (CAS603-76-9), 1-methylbenzotriazole (CAS 13351-73-0), 1-methylbenzimidazole(CAS 1632-83-3), 1-methylindazole (CAS 13436-48-1), 1-ethyl-indazole(CAS 43120-22-5), 1H-Indole, 1,5-dimethyl-indole (CAS 27816-53-1),1,3-dimethyl-indole (CAS 875-30-9), methyl1-(butylcarbamoyl)-2-benzimidazolecarbonate,1-(chloromethyl)-1H-benzotriazole, and 1-aminobenzotriazole. While thecoating promoter is optional in the present invention, if it is presentthen the uniformity enhancer can also be considered optional.

Referring to FIG. 4, the R substituents on the aromatic ring may bealkyl, hydroxyalkyl, aminoalkyl, nitroalkyl, mercaptoalkyl, or alkoxygroups containing from 1 to about 10 or more carbon atoms. The R1substituents on the heterocyclic ring bonded to the nitrogen atom at the#1 position may be hydroxyl, amino, alkyl, hydroxyalkyl, aminoalkyl,nitroalkyl, mercaptoalkyl, or alkoxy groups. Specific examples of alkylgroups include methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl,tert-butyl, amyl, etc.

The formulation of the present invention is preferably made up withde-ionized water.

The composition of the present invention does not require halogen ionsand can be essentially free of halogen ions, if desired. By “essentiallyfree of halogen ions” we mean that the adhesion promoting composition iscomposed of less than about 0.01% by weight of halogen ions. We define“halogen ions” as fluoride, chloride, bromide or iodide ions or anycombination or equivalent of these ions in aqueous solution. Inaddition, the composition of the present invention does not require asurfactant to achieve an excellent roughened copper surface.

Halogens can, however, be employed in the formulation if desired. Forexample, a small amount of chloride ion or other halide ions can be usedin the formulation. Halides can be regarded as an optional ingredient inthe present formulations.

In keeping with another aspect of the present invention, the process ofpreparing roughened copper surfaces suitable for subsequent multilayerlamination includes the following steps, some of which are optional:

(i) Providing a substantially clean copper surface, optionally byapplying a highly built alkaline cleaning solution to a copper surface.The highly built alkaline cleaning solution comprises a surfactant and aphosphate or a phosphate ester.

(ii) Optionally dipping the substantially clean copper surface into apre-dip to remove surplus cleaning solution from the copper surfaceproviding a clean copper surface;

(iii) Applying to the clean copper surface a adhesion promotingcomposition consisting essentially of an oxidizer, a pH adjuster, atopography modifier, and a uniformity enhancer, as described above.

(iv) Optionally dipping the uniformly roughened copper surface into apost-dip to provide a roughened copper surface suitable for subsequentmultilayer lamination. The optional post-dip is used to coat theroughened copper surface with a coating of organic molecules to enableenhanced bonding between the roughened copper surface and a suitabledielectric resin. The post-dip solution comprises an azole or silanecompound. The post-dip may further comprise a titanate, zirconate, oraluminate.

Step (i) may further include draining excess cleaning solution from thecopper surface.

Non-limiting examples of silanes for enhancing the bond strength betweenthe copper surface and the dielectric include any trichloro ortrimethoxy silane, especially those derivatives with at least onenitrogen atom such as trimethoxysilylpropyidiethylenetriamine. Otherexamples of silanes suitable for use in the present invention include:3-methylacryloyloxypropyltrimethoxysilane,3-(N-styrylmethyl-2aminoethylamino) propyltrimethoxysilanehydrochloride, 3-(N-allyl-2-aminoethylamino)-propyltrimethoxysilanehydrochloride, N-(styrylmethyl)-3-aminopropyltrimethoxysilanehydrochloride, N-2-aminoethyl-3-aminopropyltrimethoxysilane,3-(N-Benzyl-2-aminoethylamino)-propyltrimethoxy silane hydrochloride,beta-(3,4-epoxycyclohexyl) ethyltrimethoxysilane,gamma-aminopropyl-triethoxy silane,gamma-glycidoxypropyltrimethoxysilane, and vinyltrimethoxysilane.

Non-limiting examples of titanates that can be used in the presentinvention include: titanate amine, tetraocytl di(ditridecyl)phosphitotitanate, tetra(2,2-diallyloxymethyl) butyl-di(ditridecyl)phosphitotitanate, neopentyl(diallyl)oxytri(diocytl)pryo-phosphato titante, andneopentyl(diallyl)oxy tri(m-amino)phenyl titanate.

Non-limiting examples of suitable zirconates (available, for example,from Kenrich Petrochemicals, Inc., Bayonne, N.J.) include: KZ 55-tetra(2,2 diallyloxymethyl)butyl, di(ditridecyl)phosphito zirconate,NZ-01-neopentyl(diallyl)oxy, trineodecanoyl zirconate, andNZ-09-neopentyl(diallyl)oxy, tri(dodecyl)benzene-sulfonyl zirconate.

Further non-limiting examples of suitable zirconates include: tetra (2,2diallyloxymethyl)butyl-di(ditridecyl)phosphito zirconate, and zirconiumIV 2,2-dimethyl 1,3-propanediol.

Non-limiting examples of aluminates that can be used in the presentinvention include: Kenrich® diisobutyl(oleyl)acetoacetylaluminate (KA301), and diisopropyl(oleyl)acetoacetyl aluminate (KA 322).

The topography of the copper surface is favorably modified by thepresent compositions, over and above the typical topography achieved byperoxide based etching solutions known in the art. Also, the uniformityand completeness of the topography modification and coating are wellabove what is typically seen in the art.

The adhesion promoting composition may optionally comprise a copper saltsuch as copper sulfate. The aqueous copper ions protect virgin stainlesssteel surfaces, such as those of a process tank, from chemical attack.Hence it is advantageous to include a quantity of copper salt in theadhesion promoting composition if the copper surface to be treated isdipped into a new or previously unused steel tank. However, there is norequirement to include a copper salt to obtain a highly satisfactoryroughened copper surface.

One practical test that can be used to indicate the better adhesion ofresins to the present copper surface is the well-known tape test forpeel strength. Self-adhesive tape is adhered to a treated coppersurface, then peeled off and examined to determine how much of thetreated surface material is removed. Many conventional treated coppersurfaces, subjected to the tape test, will transfer enough material tothe tape to prevent it from adhering when subsequently placed in contactwith a hard surface. The treated surfaces resulting from practicing thepresent invention, however, commonly transfer little or no material tothe tape and do not prevent the tape from being readhered to anothersurface. This tape test result indicates that the present inventionprovides a desirable, tightly-adhering coating.

The following examples represent specific but nonlimiting embodiments ofthe present invention:

EXAMPLE 1

A copper surface was etched by 3% H202, 5% H2S04, 5 g/l benzotriazole(“BTA”), balance deionized water (“DI”), with no uniformity enhancer orcoating promoter (see Table 1). The etched copper surface wasundesirably speckled with shiny spots of copper, indicating anon-uniform etch.

EXAMPLE 2

A copper surface was etched with the following composition: 3% H202, 5%H2S04, 1.5 g/l BTA, balance DI, with no uniformity enhancer or coatingpromoter. The etched copper surface developed undesirable striationsthat were indicative of a non-uniform etch.

EXAMPLE 3

A copper surface was etched by: 3% H202, 5% H2S04, 1.5 g/l BTA, 0.5 g/l5-Aminotetrazole (uniformity enhancer), balance DI, with no coatingpromoter. The etched copper surface was desirably uniformly etched. Thisexample demonstrates the value of the uniformity enhancer.

EXAMPLE 4

A copper surface was etched using the following formulation: 3% H202, 5%H2S04, 1.0 g/l BTA, 0.5 g/l 1-hydroxybenzotriazole (coating promoter),balance DI. A SEM photograph, FIG. 5, of the etched copper surfacereveals a copper surface that has been uniformly etched and covered in acoating that is believed to be an organometallic coating.

EXAMPLE 5

A copper surface was etched, using as the etchant: 3% H202, 5% H2S04,1.0 g/l BTA, 2 g/l 1-hydroxybenzotriazole (coating promoter), balanceDI.

EXAMPLE 6

A copper surface was etched, using as the etchant: 3% H202, 5% H2S04,1.5 g/l tolyltriazole (topography modifier), 0.05 g/l 5-mercaptomethyltetrazole (uniformity enhancer), 2 g/l 1-hydroxybenzotriazole (coatingpromoter), and balance DI.

See Table 1 for a summary of examples 1 to 6.

While the invention is described above in connection with preferred orillustrative embodiments and examples, they are not intended to beexhaustive or limiting of the invention. Rather, the invention isintended to cover all alternatives, modifications and equivalentsincluded within its spirit and scope of the invention, as defined by theappended claims. TABLE 1 Example 1 Example 2 Example 3 Example 4 Example5 Example 6 Oxidizer 3% H₂O₂ 3% H₂O₂ 3% H₂O₂ 3% H₂O₂ 3% H₂O₂ 3% H₂O₂ PHadjuster 5% sulfuric 5% 5% 5% sulfuric 5% 5% sulfuric acid sulfuricsulfuric acid sulfuric acid acid acid acid Topography 5 g/l 1.5 g/l 1.5g/l 1 g/l 1 g/l 1.5 g/l modifier benzotriazole benzotriazolebenzotriazole benzotriazole benzotriazole tolyltriazole Uniformity NoneNone 0.5 g/l None None 0.05 g/l Enhancer 5-amino- 5-mercaptomethyltetrazole tetrazole Coating None None None 0.5 g/l 2 g/l 2 g/l Promoter1-hydroxybenzotriazole 1- 1-hydroxybenzotriazole hydroxybenzotriazoleD.I. water Balance Balance Balance Balance Balance Balance CommentsSpeckled Striations Uniform Uniform — — etch etch Organo- metalliccoating RESULT Defect Defect No defect No defect — —

1. A process for preparing roughened copper surfaces suitable forsubsequent multilayer lamination, said process comprising the steps of:(a) applying a highly built alkaline cleaning solution to a coppersurface to provide a substantially clean copper surface; and (b) dippingthe clean copper surface into an adhesion promoting composition toprovide a uniform roughened copper surface suitable for subsequentmultilayer lamination, said adhesion promoting composition consistingessentially of an oxidizer, a pH adjuster, a topography modifier, and acoating promoter.
 2. The process according to claim 1, said adhesionpromoting composition further consisting essentially of a uniformityenhancer.
 3. A process for increasing the adhesion of a dielectricmaterial to a metal surface, wherein the metal surface comprises copperor copper alloys, said process comprising: (a) contacting the metalsurface with an adhesion promoting composition comprising anadhesion-promoting effective amount of: (1) an oxidizer; (2) an acid;(3) a topography modifier; and (4) a coating promoter; (b) bonding thedielectric material to the metal surface which has been contacted withsaid adhesion promoting composition.
 4. A process according to claim 3wherein the adhesion promoting composition further comprises auniformity enhancer.
 5. A process according to claim 3 wherein thetopography modifier is a 5-membered aromatic fused N heterocycliccompound, wherein the N heterocyclic ring has a nitrogen atom atposition 1 bonded to a hydrogen atom.
 6. A process according to claim 3wherein the coating promoter is a 5-membered aromatic fusedN-heterocyclic compound with 1 to 3 nitrogen atoms in the fused ring,wherein none of said nitrogen atoms are bonded to a hydrogen atom.
 7. Aprocess according to claim 3 wherein the coating promoter has thefollowing structure:

wherein R1 is selected from the group consisting of hydroxyl groups,amino groups, alkyl groups, hydroxyalkyl groups, aminoalkyl groups,nitroalkyl groups, mercaptoalkyl groups, and alkoxy groups.
 8. A processaccording to claim 3 wherein the coating promoter is1-hydroxybeznotriazole.
 9. A method of preparing a printed circuit boardfor subsequent multilayer lamination, comprising the steps of: (a)providing a printed circuit board, said printed circuit board comprisingan imaged layer of copper bonded to a dielectric substrate; and (b)contacting said imaged layer of copper with a surface rougheningcomposition comprising: (1) an oxidizer; (2) an acid; (3) a topographymodifier, wherein said topography modifier is a 5-membered aromaticfused N-heterocyclic ring compound, wherein the N-heterocyclic ring hasa nitrogen atom at position 1 bonded to a hydrogen atom; and (4) acoating promoter having the following structure:

wherein R1 is selected from the group consisting of hydroxyl groups,amino groups, alkyl groups, hydroxyalkyl groups, aminoalkyl groups,nitroalkyl groups, mercaptoalkyl groups, and alkoxy groups; wherein thesurface of said imaged layer of copper is roughened by said contactingstep.
 10. The method of claim 9, wherein said surface rougheningcomposition further comprises a copper salt.
 11. The method of claim 9,wherein said contacting step takes place in a tank having stainlesssteel surfaces.
 12. The method of claim 11, wherein said surfaceroughening composition further comprises a copper salt, wherein saidcopper salt protects said stainless steel surfaces from chemical attack.